1. Field of the Invention
The present invention relates to downhole tools, and, more particularly, to a Jacquard control system for controlling the routing of fluids into/out and within a downhole tool, such as a fluid sampler and tester.
2. Setting of the Invention
The use of fluid samplers and testers connected to a wireline to perform nondestructive collection and/or testing of fluid samples from subterranean formations is well known. Representative fluid sampling and testing tools are disclosed in U.S. Pat. No. 3,294,170 Purfurst; U.S. Pat. No. 3,577,783 Whitten; U.S. Pat. No. 4,416,152 Wilson; and "New Well Logging Tools Improve Formation Evaluation" IPE Journal, Sept. 10, 1979.
Previously, downhole tools have used electrically controlled solenoid valves to control the routing of fluids into/out and within the tool. The use of this type of valve has met with various degrees of success depending upon the complexity of the tool, as well as the tool's operating environment. One of the major problems with using this type of valve has been fouling of the valve by the corrosive and high-solids content borehole fluids. There is a need for a valving arrangement which prevents the occurrence of such fouling. As the benefits of using these tools has become more widely accepted the demand for fluid samplers and testers has grown. Various new tools have been developed which have increased capabilities and thus their internal fluid control complexity has grown. Working against this demand for increasing the functional capability of these tools is another demand that the overall outside diameter of these tools be reduced to enable the tools to operate in smaller diameter exploratory holes. As these tools have become more complex, it has become more difficult to package the fluid control valves and all of the necessary fluid piping within a smaller and smaller package. There is a need for a simple, rugged, small-sized fluid control mechanism for use within the downhole tool to control the routing of fluids into/out and within the downhole tool, and reduce the number of solenoid valves and the amount of tubing and pipe connections within the downhole tool.